It is known that 2,4-dimethyl-3-cyclohexene-1-carboxyaldehyde, represented by the following formula (II): ##STR4## has a strong leaf-like green aroma (see Perfume and Flavor Chemicals I by Steffen Arctander No. 996). However, the compound of the above formula (II) is disadvantageous because it contains a formyl group making it unstable.